Proximity-based service (ProSe) direct communication, such as device-to-device (D2D) communication, in a cellular network usually refers to a service for directly transmitting user data between terminals without a network transit. The D2D communication reduces a load of a base station, and remedies a defect that it is unable to perform effective communication between cellular devices outside a coverage of the base station.
The D2D communication may be applied to a variety of scenarios including for example: traffic data at a user plane may be directly transmitted locally without going through a network side, to for example achieve offloading of cellular network traffic; wireless communication between terminals is ensured with the D2D communication in a case where infrastructure of a traditional communication network is damaged due to a natural disaster; and an enhanced D2D communication for the Internet of Things, etc. In particular, as a typical application scenario of the Internet of Things, the D2D communication may include communication between a vehicle and an associated entity (V2X communication). The V2X communication may include, for example, vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V21), and vehicle-to-pedestrian (V2P) communications, etc.